Fluidized conversion and coking of heavy petroleums



Aug. 5, 1952 F. w. I EFFER 2,606,144

. FLUIDIZED CONVERSION AND COKIN@ oF HEAVY PETROLEUMS Filed Deo. l0. 1949 Patentecl Aug. 5, 1952 FLUIDIZED CONVERSION AND COKNG OF HEAVY PETROLEUMS Frederick W. Lefer, Riverside, Ill., assigner to Universal Oil Products Company, Chicago, lil., a corporation of Delaware Application December 10, 1949, Serial No. 132,309

16 Claims.

This invention relates to an improved process and means for effecting the fluidized conversion and coking of relatively heavy petroleum charging stocks. More specifically, the improved process and means are provided for a continuous conversion of charging stocks such as topped crude, reduced crude, Bunker C fuel, and the like in a iiuidized bed of solid particles to form more desirable lower boiling products and coke in the form of nely divided particles.

Various uidized coking operations are known in the art which are continuous and of appreciable advantage over the earlier types of fixed bed coking, where a solid mass of coke deposit was allowed to build up on the walls of a coking chamber. However, the known iiuidized coking operations generally utilize two or more separate contacting chambers and other devices for eiecting the desired conversion reactions, the sizing of solid particles suitable for withdrawal as product or for further treatment, respectively, and the heating required foi-'supplying the endothermic heat of the conversion reactions, while various ducts or conduits have been necessary to convey the particles from one chamber to another or to and from particle separating and grinding or sizing devices to permit a continuous operation.

It is a principal object of the present invention to provide a process for the continuous conversion and coking of relatively heavy petroleumV stocks and similar high boiling or residual hydrocarbon materials wherein the solid particle mixture resulting from the conversion and coking reactions is segregated by diierential settling in a fluidized bed into relatively heavy or coarse particles to be withdrawn as a product of the process upon drying or hardening, and into finer or lighter particles which are recirculated through the conversion and coking zone to permit the additionalbuild-up of coke thereon.

Pursuant to this principal object the present invention provides 'for the conversion and ook# ing of heavy hydrocarbon stocks of the aforesaid kind in arfluidized particle bed serving at thersame time the effective performance of the conversion and coking reactions and the continuous segregation of relatively iine solid particles desired as nuclei for coke deposition from coarse particles desired as a productv of the process. Thus the invention aims at obviating the segregation of nuclei forcoke deposition by means of .particle screening, grinding or other sizing devices which, due to their complicated structure and their. arrangement outside the chamber containing the coking zone, constitute the source of substantial heat losses and mechanical difculties in a continuous ow system and require frequent inspectionk and repair in order that they may be maintained in working order.

Another important object of the present invention is to provide for the iiuidized contacting of relatively heavy hydrocarbon stocks to effect the conversion and coking of the latter to desired products in a coking zone coordinated with adjacent and contiguous zones for the drying or hardening of the desired coke product and for the recirculation of fine particles, respectively, in a manner providing heat exchange between these zones and substantially eliminating a plurality of transfer conduits or pipes between these zones.

.A further object oi the invention is to provide the fluidized operation within a single confined contacting chamber which is partitioned into the-desired contacting zones adjacent to and in heat exchange relationship with one another in a manner to obtain maximumutilization of heat and a highconversion eiciency.

Still further, it is an `objectcof the invention to provide anzimproved apparatus particularly suitable for. performing the process herein described and having transfer means in the form of an open ended conduit in a substantially vertical and preferably central position to eiect the recirculation of the finer subdivided particles, such that they are returned from an upper segregation zone in a straight line flow to the lower end portion of the coking and conversion zone. l

Principally, the present invention provides an improved process for converting and coking a heavy hydrocarbon charge stream which comprisesfluidizing nely divided solid particles by a gaseous-heating and iiuidizing medium in a bed ascending through a coking zone into a segregation zone Yopenly communicating with the coking Zone, introducing the charge stream into the lower portion of the fluidized bed within the coking zone and converting `itinto lower boiling products and coke depositing on said particles during intimate contact with the heating and iiuidizing medium, segregating resultant coarser from finer particles in the iiuidized bed in the segregation lZone, discharging coarser particles continuously from the lower portion of the segregation zone into a coniined driving Zone and therethrough from the process, withdrawing nner particles continuously from the upper portion of the uidized bed in the segregation zone and re- 3 turning them in a confined dense phase stream to the lower portion of the coking zone and the uidized bed therein, disengaging vaporous products upwardly from the fluidized bed and withdrawing them from the upper portion of the segregation zone.

In a specific embodiment the process of the present invention comprises p-assing a heavy hydrocarbon charge stream concurrently upwardly in a coking zone together with 'finely divided particles and a gaseous heating and uidizing medium within an upwardly moving uidized bed and therein effecting a high temperature conversion of the hydrocarbon charge stream to desired more valuable vaporous products and a coke deposition on the particles, discharging the fluidized bed comprising the resulting products and coked particles into a segregation zone above and openly contiguous with the coking zone, withdrawing the heavier coked particles from the lower portion of the segregation zone and passing them downwardly through a conned drying zone adjacent to and in indirect heat exchange relationship with the coking zone, withdrawing relatively ne coked particles from the top portion of the fluidized bed in the segregation zone and passing them in a relatively dense phase confined column extending downwardly through the coking zone to the lowel` portion thereof and recirculating them upwardly within the coking zone, discharging vaporous products from the upper portion of said segregation zone, and withdrawing excess coked particles from the lower portion of the drying zone.

In a preferred operation and arrangement' of zones, the drying zone has an annular shape circumscribing the coking zone, such that a single confined chamber may be used to enclose the desired contacting zones. Also, the conduit withdrawing the finely' divided particles from the upper portion of the segregation zone is preferably located concentrically within the coking. zone such that the particles to be .recirculated are brought in a conned straight line path to the lower end of the coking zone and distributeduniformly thereto. The finely Vdivided particles which are first charged to the unit may `be any inert material, but preferably are comprised of iinely divided coke particles such that as coke is deposited on them and built up to provide larger particles they may be withdrawn from the unit in a continuous manner and provide a net production of usable coke material.

The particle separation in the segregation zone, which is maintained above the coking and dryingzones, is brought about by reducing the rate of upward travel ofthe uidized bed in the segregation zone and relative to that vin the coking zone to such an extent that the simultaneous withdrawal of a separate stream of particles from each of the upper and lower portions of the nuidized bed in the segregation zone causes the heavier, coarser particles to settle at a greater rate than the finer particles and to travel downwardly while the finer particles are more strongly hindered A'by the gaseous and vaporous products ascending from the coking and drying zones from settling and are largely carriedA to the top portion of the luidized bed wherefrom they are drawn into "the open top end of the fine particles withdrawal conduit; The reduction of the rate of upward travel of the iiuidized bed is attained by providing the segregation zone with a larger cross-sectional area than the coking zone, the enlargement exceeding' substantially stantially lower in the drying zone than in the coking zone, and also the volumetric rate of upward iiow of gasiform material per unit .weight of solid particles in contact therewith is materially less in the drying zone than in the coking zone. Consequently a substantial reduction in the rate of upward travel of the uidized bed on passing from the coking zone into the segregation zone and a fairly satisfactory particle separation resulting thereby are attainable already when the cross-sectional area of the segregation zone is about equal to the sum of the cross-scctional areas of the coking zone and the drying zone. In the preferred embodiments of the present4 invention, however, a more drastic diifer.- ential settling or more distinct particle separation is assured by providing the segregation zone with a cross-sectional area substantially larger than the combined cross-sectional area of the coking and drying zones.

The hot fluidizing and heating gas passing upwardly with the particles and hydrocarbon stream in the coking zone is preferably an inert stream, suchas stream, and is supplied at a sufcient rate to maintain thedesired iluidization and at a temperatiu'e suiiicient for effecting the desired conversion and coking of the hydrocarbon stream in thepres'ence of the subdivided particles. When such steam or other inert gas is utilized in the coking zone, this gasiform medium is preferably heated to the nal high temperature outside of the coniined chamber by means of combustion gases generated by burning cokeY or other less 4valuable combustible byproducts of` the process, or by other means as will be more fully` explained hereinafter.

Pre-heating of the charge streams or at least a portion thereof may be effected through heat exchange relationship with resulting product streams. Thus, indirect heat exchange may be eiected between the hydrocarbon charge stream and the gaseous and vaporous product stream from theupper portion ofthe segregation zone, while inert fluid for use as inert gaseous heating vand luidizing medium in thel coking zone and/or as gasiform'drying and ae-rating medium in the drying 'zone may be pre-heated by direct heatexchange with the hot net coke being withdrawn from the lower portion of the drying zone. Inert huid, moreover may be pre-heated first by direct heat exchange with the hot net coke issuing from the drying zone and then by indi- Arect heat exchange with the hot gasiform product stream issuing from the top portion of the segregation zone, the thus pre-heated inert fluid being then use'd as drying and aerating medium in the drying zone and in the ne particles with.-vv drawal conduit. In' the latter mode of heat utilization the partially'cmool'ed gasiform product streamniay then be brought into direct or inl direct fhea't exchange Vwith the hydrocarbon charge stream to pre-heat the latter prior to fractionation of the former. l

While previous types of iiuidized coking units provide Imeans forl recirculating coke vas nuclei to a conversion and coking zone, the present ar- 525? rangement provides advantageous featuresover former arrangements in that the nner or less coarse particles are selectively withdrawn from the segregating zone by internal conduit means and ina manner which precludesloss of heat therefrom and redistributes them uniformly at the lower end of the coking zone. The heavierv Withinthis drying zone, the coke is freed fromV entrained' or absorbed hydrocarbon vapors and transformed into hard particles of low volatile content by contact with an inert gaseous medium such as substantially oxygen-free flue gases or preferably steam at approximately the temperature prevailing within the coking zone.

The gasiform mixture which is discharged from the upper portion of the segregation zone lis passed to suitable separating and fractionating equipment. However, in a preferred mode Yof carrying out the present invention, this gasiform product stream is passed in heat exchange relationship with the hydrocarbon charge stream, or alternatively, in heat exchange with at least a portion of the charge streams being passed to the lower portion of the drying and aerating gas distribution nozzles which in turn are utilized to distribute drying or devolatilizing gases uniformly to the annular shaped drying zone. The use of aV single confined chamber to enclose the essential contacting zones is of course economical from the standpoint of simplicity, relative to the use of a plurality of separate contacting chambers and'supports or superstructurestherefor, and in addition effects the elimination of long transfer conduits between separated zones.

Reference to the accompanyingk drawing and the following description .thereof lwill serve to more clearly point out the operation of a preferred embodiment, as well as indicate or clarify various. features and advantages obtained by the present uidized operation.

Referring now to the drawing, there is shown a, vertically disposed and` confined chamber I, having the upper portion thereof somewhat enlarged in diameter and providing a vparticle segregation, section 2. Within the lower elongated vportion of the chamber and spaced from the outer wall is a cylindrical baiile or partition 3, which in turn separates the lower portion of the unit into an annular shaped particle drying section 4 and a coking section 5. The baflle member 3 forms a seal between the lower portions of the drying section and the coking section. The lower portion of the baffle member 3 is of somewhat smaller diameter and is indicated in this drawing to extend somewhat below the lower head of the external chamber I, in order Yto provide a suitable inlet section 6 at the lower end of the coking zone. Positioned centrally within and vertically through theI coking zone and extending downwardly into the inlet section 6, is an open-ended conduit or particle return leg 1 having its open upper extremity extending above the partitioning wall 3, in a manner suitable to permit the withdrawal of the finer or lighter coke particles which are carried to the upper portion of the particle segregation zone 2; As hereinaftervdiscussed more fullyin'connectionwith the' operation of the unit,

the conduit 'I provides for the continuous'recircu-- lation of the finer particles within `the unit into the inlet end of the coking zone. Also, ashas= been noted, nely divided coke-particle's'are 'preferably charged to theunit initially to provide the necessary nuclei for 'aiding in the conversionl of and coke deposition from a relatively heavy hydrocarbon charge stream,.new nuclei being thereafter formed by the coking reactionslfln addition to the deposition of'coke on particles already present.

The hydrocarbon charge stream is introduced into the lower end of the coking zone by means of inlet line 8,y having control valve 9, and suit-'- able distributing means I0 effectingA the substan-r tially uniform introduction of the material into the lower end of thezone and into contact with the upwardly fiowing particles.r As hereinbefore noted, the hydrocarbon charge stream may bea 500 to labout '700 F. or generally to a temperaturel below active coking temperature and may thus bel more or less vaporized prior to introduction into the ccking zone for conversion into desired gasiform cracked products and coke deposition onI A gasiform heating medium suit- 1 the particles. able to supply the endothermicheat. requirements withinthe 'coking and conversion' zone is supplied through yline II, having "valveaIZ, and is.Y distributed uniformly within the inlet fsection. 6'- The latter operates also to by a distributor I3. uniformly fluidize and aid in the circulation of the particles descending through theV recircu-4 lating leg 'I to the lower end of the coking zone. The preferred heating and -fluidizng medium introduced to this zoneby wayof line IIV isa high temperature inert'gas 'or .steam at about 1000i FLY-1200" F. or more, which has beeniheated in-a zone external of the conversion zone 5 and chamber I and which maintains the fluidized bed atV activecoking temperature, usually within the range of from aboutv850 to 1000 F. f The heating of the fluidizing and heat supplyingmedium to the desired elevated temperature preferably is effected outside of the chamber I by the combustion of low value by-productsvof the process, or of a portion of the coke produced.

Alternatively, heat may be generated in the col:-` ing and conversionzone itself vby the introduction of an oxygen containing gas, such as air o-rA a gas having `a higher orv lower free oxygen content thanair,such that -a controlled portion ofi. the combustible materials present in the iluidized bed in the coking zone may be burned to supply the endothermic heat requirements within this zone and maintain the ascending lluidized be therein at active coking temperature. c

Sufficient reactant charge and heating gas isr supplied to the chamber to maintain fluidization therein at a level, as indicated bythe broken line I4, which is-above the upper extremity'of the -fine particles return legi. However, the fluidization is coordinated with respect, to the size and crosssectional area of the conversion, drying and particle segregating zones, such that the velocity of the particles is reducedin the latter zoneto permit substantially only thel finer particles to be carried to 'the upper level ,of the relatively dense phase iluidized bedv and thus be subject to recirculation downwardlythrough theconduit 1. Someaerating eas may, be suppliedA through line 4I ,and valve .42 to'paess into` the return leg 'I x in orderv to ,prevent clogging or undue compacting ofthe particles as they descend in the leg. -In a preferred operation the fine particles arepermitted to now downwardly by gravity in a relatively compact columnA conned by a relatively` small; diameter straight conduit being placed concentricelly within the coking zone.

The resulting conversion gases and vapors are continuously withdrawn from the upper portion ofthe segregation zonel 24 by way of a suitable particle separating apparatus I5, connecting with a suitable. outletline I'I' having control valve I8, and: recovered particles are returned tothe return leg 'I through dip leg I6. In accordance wlththeA preferred operation of the unit, the

gasiform product stream passes through heat exchange means I!!` and isA subsequently discharged through conduit 20, which carries the stream to suitable fractionating and separating equipment. Steam or other substantially inert gasiformV medium may be passed through line 2| having controly valve, 22, and .through the heat exchanger I9.- to be., subsequently passed to the lower end' of the drying section byv way of lines 23 and 24, having, respectively valves 25y and 26, with suitablel distributing rings or headers 21 and 218 arranged toV uniformly introduce the medium into the annular zone. Thedrying and aerating gas passing tof this zone need not be at a high temperature, with respect tothe. coking and conversion zone, for sufficient heat is transferred by heat. exchange within the chamber I from the coking zone-to the drying zone to maintain in the lattera temperature .of the order 0f.7509 Vto 950 E .zwhich is in general suiicient to devolatilize the coarse Vcoke particles descending in this drying zone and provide a desire form of hard, granular coke, that may be withrawnfrom the unit.

Although' excess coke particles which are accumulated inand withdrawn from theA lower endof the chamber I may be used as moisturefreefparticulatedcoke, it is economically desir' able to pass the coke particles downwardly by Way of. line 28 and control va1ve-30 to the interior of 'a quenching and steam generating chamber 3I, whereby heat may be withdrawn from the discharged particlestream for use within the unit. A suitable Aquenching medium such as water is introduced into the lower portion of the chamber. 3I by way. of line 32 and control valve 33A so as to countercurrently contact the descending-.bed of coke particles' and erfectsimultaneously the,A cooling of the lattervand the generation of, low temperature steam Within the unit. Resultingf steam is withdrawn. through a suitable particle separator 34 andoutlet line SEQ-'while resultingY cooled coke particles maybe withdrawn from the lower portion of the quenching and steamgeneratingchamber by means of an outlet line 36 and controlvalve 31. Anotheradvantage of the water cooling is `that the coke material may be withdrawn from the cooling chamber in a slurry stream.

The steam discharged by way of line 35 may be passedto a suitable steam collecting drum for use in the processing plant, with flow regulated..

by control vali/e323. However, in accordance with the preferable operation of .the present:

ccking and conversion unit, at least a part of the steam is utilized to provide heating steam,

or drying and aeratingsteam within the drying zone. The low temperature steam is passed by way of the transfer line 39 and control valve 40 to line 2 I and via the latter conduit through the heat exchanger I9 for an increase in temperaturel and subsequent distribution through conduit 23.v Y

It may also be noted that a portion of the generated steam, or other externally supplied drying and aerating gas is passed through line 23 and may be distributed, by way of line 4I and controlvalve 42, into the lower end of the coking and conversion section, at the inlet section 6, in order to provide additional aerating medium in that section as well as to provide means for aerating the material descending in the return legi.

The coking operation of the present embodiment may be carried out at any desired subatmospheric, substantially atmospheric, or superatmospheric pressure. It is preferable to operate the unit at a low superatmospheric pressure, of the order of l0 to 75 pounds per square inch, which is suncient to permit the fractionation of the gasiform product stream at above atmospheric pressures.

In order to obtain desirable operating conditions, it is also necessary-to coordinate and regulate the cross-sectional area of the various particle npassage ways and contacting zones. The free cross-sectional area of the conversion and cokingl zone` 5 is intermediate to the free crosssectional areas of the,` segregation zone 2 and the d ryingY zone 4, and preferably the free crosssectional area of the segregation zone is larger than. the combined cross-'sectional areas of the coling and drying zones, with the coking zone beingpf the order of about twice the cross-sectionalV area of that of` the drying zone.. These proportions permit; the proper intense iiuidization within the ccking zone relative to a less` intense uidizationvwithinthe segregaton zone, the fine, particles returnA leg, and the drying zone. A relatively densemoving contact bed of material may be accommodated in the drying zone. T-hus, the.. density' of, the uidized bed within the coking, zone is always ,'rnaintained` appreciably lower than the densities of the descending. masses. withinY the particle return leg 'I and within they annular columnof material in the drying. zone 4. Although the accompanying drawing inageneral way indicates a preferredrelation between the diameters of theprincipal contacting zones, this drawing is. not Atoscale, andit is to be understood that the arrangementv and proportion of zones which is shown are notto be considered limiting.

The present operation and arrangement of zones, while particularlyy advantageous for the cokingV and conversion of relatively heavy fuels, need not be limited to that tuse` only, for other processing-.operations which may be carried out inV a fluidized manner may well make use of the compact arrangement ofzones and the economicalmanner of flow. However, coke which isproduced in a 'manner as has-been describedprovidesA a. substantially pure form of coke which is desirable asa metallurgical coke, or-alternately as4 y hydrocarbon charge stream which comprises 'fluidizing finely divided solid particles by a gaseous heating'and fluidizing medium in a con- Y ,'tinuous bed ascending through a coking zone into al segregation zone openly communicating with saidA` coking zone, introducing said charge stream into theflower portion of the fluidized bed within V 'said coking zone and'converting it into lower boiling'products and coke depositing on said particles during intimate contact with said heating and fluidizing medium, reducing the rate of upward fr travel of said iluidized bed in the segregation zone and segregating'resultant coarser from ner particles in the fluidized bed in said segregation zone,

discharging coarser particles continuously from the lower portion of said segregation zone into a conned drying zone and therethrough from the process, withdrawing finer particles continuously from the upper portion fo the iluidized bed in said segregation zone and returning them in a downwardly moving conned dense phase stream to the lower portion of the coking zone and the fluidized bed therein, and disengaging vaporous products upwardly from said fluidized bed and withdrawing themirom the upper portion of said segregation zone; l' '2. A process for converting and coking a heavy hydrocarbon charge stream which comprises fluidizing finely divided solid particles by a gaseous heating and fluidizing medium in a continuous bed ascending through a coking zone into a segregation zone openly communicating with saidy coking zone, introducing said charge stream into the lower portion of the fluidized bed within said coking zone and converting it into lower boiling products and coke depositing on said particles during intimate contact with said heating and fluidizing medium in said coking zone, reducing the rate of upward travel of said uidized bed A-them in a downwardly moving confined dense Vphase stream to the lower portion of the coking zone and the iluidized bed therein, and disengaging vaporous products upwardly from said fluidized bed and withdrawing them from the upper portion of said segregation zone.

3. A process for converting and coking a heavy hydrocarbon charge stream which comprises fluidizing nely divided solid particles by a gaseous heating and fluidizing medium in a continuous bed ascending through a coking zone into a segregation zone openly communicating with said coking zone, introducing said charge stream into the lower portion ofthe fluidized bed within said coking zone and converting it into lower boiling lproducts and coke depositing on said particles during intimate contact with said heating and iluidizing medium in said coking zone, reducing the rate of upward travel of said fluidized bed in the segregation zone and segregating resultant coarser from finer particles in the iluidized bed in said segregation zone, discharging coarser particles continuously from the lower portion of said segregation zone into a conined drying zone and therethrough from the process, withdrawing finer particles ycontinuously from the upper portion of the uidized bedv in said segregation zone and passing them in a-dense phase stream through a confined path extending downwardly through said fluidized bed to the lower portion of the cokingzone, discharging said dense phase stream from said conined path into the fluidized bed ascending in said coking zone, and disengaging vaporous products upwardly from said fluidized bed and withdrawing them from the upper portion of said segregation zone- 4. A process for converting and coking a heavy hydrocarbon charge stream which comprises, passing said stream concurrently upwardly in a coking zone together with finely divided particles and a gaseous heating and uidizing medium within anvupwardly moving fluidized contacting bed and therein eiecting a high temperature conversion of said hydrocarbon charge stream to desired vaporous products and a deposition of coke on said particles, discharging the fluidized bed comprising the resulting products and coked particles into a segregation zone above and openly contiguous with said coking zone, withdrawing the heavier coked particles from the lower portion of said segregation zone and passing them downwardly through a confined drying zone adjacent to and in indirect heat exchange relationship with said coking zone, withdrawing relatively fine coked particles from the top portion of said bed within said segregation zone and passing them in a relatively dense phase confined column extending downwardly through said coking zone to the lower portion thereof and recirculating them upwardly within said coking zone, discharging vaporous products from the upper portion of said segregation zone, and withdrawing excess coked particles from the lower portion of said drying zone.

5. The method of claim '4 further characterized in that said ine particles withdrawn from said segregation zone are passed in a straight line confined column to the lower end of said coking zone for recirculation therethrough.

6. A method for converting a, relatively heavy hydrocarbon charge stream into lower boiling productsand coke which comprises, dispersing said stream concurrently upwardly in a coking zone with finely divided coke particles and a gaseous heat supplying and fluidizing medium within a continuous iluidized contacting bed extending through said coking zone into a segregation zone maintained above and openly contiguous with said coking zone, converting the dispersed charge stream into lower boiling gasiform products and a deposition of coke on the particles within said fluidized bed, withdrawing the heavier coked particles from the lower portion of said segregation zone and passing them downwardly in an annular column through a confined drying zone maintained adjacent to and concentrically around said coking zone and in indirect heat exchange relationship therewith, withdrawing linely divided continuously withdrawing -excess coked particles from the lower portion .of said drying zone.

7. The method'oi claim G further characterized in that said -heat supplying and iiuidizing medium comprises high temperature steam.

8. The method of claim 6 further characterized in that said heat supplying and uidizing medium comprises a stream containing free oxygen.

9. The method of claim 6 further characterized in that atleast a portion of the drying and Vaerating .gas stream being introduced into the lower portion of said drying zone is nrst passed in indirect heat exchange relationship with the hot product stream being discharged from the upper portion of said segregation zone, and said gaseous .heat supplying and iiuidizing medium introduced into the lower portion of said coking zone comprises a hot inert gaseous medium heated within heating means `external to said coking zone.

10. The method of claim 9 further characterized in that said coked particles being withdrawn from the lower portion .of said drying zone are continuously discharged into a separately confined steam generating zone wherein said particles are countercurrently contacted with an aqueous liquid whereby to generate steam, at least a. portion of said generated steam is passed in heat exchange with said product stream, and resultant high temperature steam is introduced as drying an aerating gas into the lower portion of said drying zone.

ll. A unitary apparatus suitable for-effecting iiuidized conversion and coking of a heavy hydrocarbon stream vin the presence of finely divided solid particles, which comprises in combination, a conned vertically disposed contacting chamber having a partition positioned concentrically within the lower portion thereof and forming an internal contacting section and an external annular shaped contacting section, a particle segregation section within the upper portion of said chamber above and openly contiguous with each of said contacting sections, a vertically positioned open-ended conduit having its upper end extending above the upper extremity of said partition with the lower end of said conduit terminating within the lower portion of said intern-al contacting section, a gas outlet from the upper portion of said segregation section, fluid inlet means at the lower end of each of said contacting sections, and particle outlet means from the lower portion of said external section.

l2. A unitary apparatus rsuitable for effecting fiuidized conversion yand coking of a relatively heavy hydrocarbon stream in the presence of iinelr,1 divided solid particles, which comprises in combination, a coniined cylindrical and vertically disposedcontacting chamberhaving a circular partitioning member positioned concentrically within the lower portion thereof and forming an internal contacting section and an external contacting section, and an enlarged cross-sectional area particle segregation section within the upper portion of said chamber above and openly contiguous with each of said contacting sections, a vertically positioned open-ended conduit placed concentrically within said internal contacting section, said open-ended conduit having its upper extremity extending abo-ve the upper end of said circular vpartition and the lower end .of vsaid open-.ended conduit terminating within the lower portion :of

said internal contacting section and Aadapted for recirculation of iine particles from the upper portiost of a fluidized bed maintained within said chamber downwardly to the lower end thereoif,v a product gas 'outlet from the upper portion of said segregation section, fluidrinlet and distributing means at the lower end of'each of said internal and external contacting sections, said distributing means being .arranged to uniformly distribute fluid to each of said contacting sections, and particle outlet means from the lower portion of said annular shaped Vexternal section suitable for the continuous withdrawal of particles from said chamber.

13. The apparatus of claim 12 further characterized in that said internal contacting section has a greater cross-sectional area than said .external annular shaped section, and said segregation section has a greater cross-sectional area than the combined cross-sectional areas ot the internal and annular shaped external contacting sections.

lll. The apparatusof claim l2 further characterized in that a particle separating means connects with said product gas outlet, and a particle return conduit extends from said particle sepa.- rating means into the upper portion of said openended conduit for the recirculation of ne particles to the lower end of said internal contacting section.

15. The apparatus of claim 12 further charactei-ized in that heat exchange and conduit means connect with said product gas outlet and with said fluid inlet means at the lower end of said contacting sections to provide heat exchange between uid to be introduced to the latter and a, gasiform product stream removed from the upper portion of said segregation section.

16. T)The apparatus of claim l5 further characterized in that said particle outlet conduit from the lower portion of said external contacting section connects with a particle quenching chamber, a. fluid inlet connects with the lower end of said quenching chamber in a manner permitting the countercurrent contact of hot particles passing downwardly through said chamber, an outlet forgasiform material from the upper portion of said quenching chamber connects with said heat exchange means for said gasiforrn product stream from the upper portion of said segregation section, and conduit means from said heat exchanger connects with the lower ends of each of vsaid internal and external contacting sections to permit supplying a heated aerating medium thereto.

FREDERICK W. LEFFER.

REFERENCES CITED The following references are of record in the of this patent:

UNITED STATES PATENTS Number Name Date 2,362,270 Hemminger Nov. 7, 1944 2,423,872 Gunness Oct. 14, 1947 2,445,328 Keith July 20, 1948 2,459,824 Leiter Jan. 25, 1949 2,433,485 Barr Oct. 4, 1949 

1. A PROCESS FOR CONVERTING AND COKING A HEAVY HYDROCARBON CHARGE STREAM WHICH COMPRISES FLUIDIZING FINELY DIVIDED SOLID PARTICLES BY A GASEOUS HEATING AND FLUIDIZING MEDIUM IN A CONTINUOUS BED ASCENDING THROUGH A COKING ZONE INTO A SEGRATION ZONE OPENLY COMMUNICATING WITH SAID COKING ZONE, INTRODUCING SAID CHARGE STREAM INTO THE LOWER PORTION OF THE FLUIDIZED BED WITHIN SAID COKING ZONE AND CONVERTING IT INTO LOWER BOILING PRODUCTS AND COKE DEPOSITING ON SAID PARTICLES DURING INTIMATE CONTACT WITH SAID HEATING AND FLUIDIZING MEDIUM, REDUCING THE RATE OF UPWARD TRAVEL OF SAID FLUIDIZED BED IN THE SEGREGATION ZONE AND SEGREGATING RESULTANT COARSER FROM FINER PARTICLES IN THE FLUIDIZED BED IN SAID SEGREGATION ZONE, DISCHARGING COARSER PARTICLES CONTINUOUSLY FROM THE LOWER PORTION OF SAID SEGREGATION ZONE INTO A CONFINED DRYING ZONE AND THERETHROUGH FROM THE PROCESS, WITHDRAWING FINER PARTICLES CONTINUOUSLY FROM THE UPPER PORTION TO THE FLUIDIZED BED IN SAID SEGREGATION ZONE AND RETURNING THEM IN A DOWNWARDLY MOVING CONFINED DENSE PHASE STREAM TO THE 